This application claims priority to an application entitled xe2x80x9cPHOTODIODE DETECTOR AND FABRICATION METHOD THEREOF,xe2x80x9d filed in the Korean Industrial Property Office on Jan. 8, 2002 and assigned Serial No. 02-958, the contents of which are hereby incorporated by reference.
1. Field of the Invention
The present invention relates to a photodiode detector and, particularly, to a photodiode detector for receiving light and converting the same into an electrical signal in an optical communication system.
2. Description of the Related Art
A photodiode having InGaAs/InP elements in series to form a photoelectron integration circuit is useful in the applications of signals for transmission in a long wavelength region ranging from 1.3 xcexcm to 1.5 xcexcm. The development of the optical communication system is growing fast as optical components (i.e., the photodiode) responsible for a faster data transmission, more bandwidth and noise determining capability have been improved. The bandwidth is defined as a wavelength(Hz) measured in a middle point of the maximum signal transmitted in the optical communication system. Such bandwidth is greatly influenced by capacitance and resistance effects. As all optical elements are made on a small scale, the influence on the bandwidth by the resistance effect is negligible. Therefore, the capacitance effect become a relatively important factor in influencing the transmission speed.
FIG. 1 is a vertical cross-sectional view illustrating a photodiode detector according to an embodiment of a related art. In particular, a photodiode detector with a mesa structure is shown.
As shown in FIG. 1, the conventional photodiode detector includes an InP substrate 3, a u-InGaAs absorption layer 2, a P-InP layer 1 stacked in series, and a SiNx film 4 used for insulation. Note that the P-InP layer 1 and the u-InGaAs absorption layer 2 are etched when forming the detector circuit. Further, a P-metal layer 5 is stacked on the upper portion of the P-InP layer 1, and an N-metal layer 6 together with a SiNx non-reflection layer 7 is deposited on a lower portion of the InP substrate 3.
The foregoing mesa structure grows the P-InP layer 1 using a single crystal growth process without the need for diffusing the operation. Therefore, the process of manufacturing the mesa structure tend to be simple. However, the P-InP layer and the u-InGaAs layer must be etched and thus exposed to the atmosphere during the manufacturing process, and also joins to the SiNx, insulation film. As such, if the InGaAs film having a small energy band gap is utilized, a current leakage is increased, thereby deteriorating the reliability of the photodiode detector.
The present invention overcomes the above-described problems, and provides additional advantages, by providing a photodiode detector and its related fabrication method without using the etching process for a single crystal of a diode in order to maximally suppress the current leakage.
A further aspect of the present invention is to provide a planar-type photodiode detector and fabrication method thereof, which is capable of receiving high speed signals.
According to another aspect of the invention, a planar type photodiode detector includes: an InP substrate; an u-In.sub.0.53Ga.sub.0.47As layer grown and stacked on the InP substrate; an InP layer stacked on the upper portion of the u-In.sub.0.53Ga.sub.0.47As layer; a SiNx insulation layer stacked on the upper portion of the u-InP layer; an additional insulation layer stacked on the upper portion of the SiNx insulation layer; a P-InP layer formed by Zn diffusing on the u-InP layer portion below an opening formed on a predetermined position between the additional insulation layer and the SiNx insulation layer; a P-metal layer positioned on an upper portion of the additional insulation layer; and, an N-metal layer formed on the lower portion of the InP substrate together with a non-reflection layer.